Flame detection system, reporting system, flame detection method, and non-transitory storage medium

ABSTRACT

A flame detection system includes a determiner and an outputter. The determiner is configured to, when image processing performed on image data detects ultraviolet light, determine that a light emitting source is a fire flame. The outputter is configured to output a determination result by the determiner.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is based upon and claims the benefit of priorityof Japanese Patent Application No. 2018-053553, filed on Mar. 20, 2018,the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to flame detection systems,reporting systems, flame detection methods, and non-transitory storagemedia and specifically, to a flame detection system for detecting a fireflame, a reporting system, a flame detection method, and anon-transitory storage medium.

BACKGROUND ART

A flame detector configured to distinguish between a flame andartificial light is known (see, for example, JP H08-307757 A). The flamedetector described in JP H08-307757 A includes an imaging opticalsystem, an image capturing means, and a flame determination means. Theimage capturing means is a color TV camera for capturing images in aprescribed monitoring range by using the imaging optical system. Theflame determination means binarizes a video signal from the imagecapturing means and determines whether or not an object is a flame basedon a time sequential pattern of a binary signal thus obtained.

The flame detector (flame detection system) described in JP H08-307757 Afocuses on that a flame moves from side to side, and thereby, flamedetector distinguishes between the flame and artificial light. Thus, inthe case of a flame (e.g., a fire flame) that does not move from side toside, the flame may not be distinguished as being a flame.

SUMMARY

It is an object of the present disclosure to provide a flame detectionsystem, a reporting system, a flame detection method, and anon-transitory storage medium storing a computer program which areconfigured to improve the detection accuracy of a fire flame.

A flame detection system according to one aspect of the presentdisclosure includes a determiner and an outputter. The determiner isconfigured to, when image processing performed on image data detectsultraviolet light, determine that a light emitting source is a fireflame. The outputter is configured to output a determination result bythe determiner.

A reporting system according to one aspect of the present disclosureincludes the above-described flame detection system, a solid-stateimaging device, and a reporting unit. The solid-state imaging device issensitive to ultraviolet light and is configured to output the imagedata. The reporting unit is configured to report an abnormality inaccordance with an output result from the outputter.

A flame detection system according to one aspect of the presentdisclosure includes a solid-state imaging device, a determiner, and anoutputter. The solid-state imaging device includes first pixels andsecond pixels arranged in a two-dimensional grid pattern, and the secondpixels are provided with filters. The determiner is configured to createfirst image data from first pixel information of the first pixels. Thedeterminer is configured to create second image data from second pixelinformation of the second pixels. The determiner is configured todetermine, based on a luminance value of each of the first image dataand the second image data, that an area from which light having a firstwavelength is emitted represents a fire flame. The outputter isconfigured to output a determination result by the determiner.

A flame detection method according to one aspect of the presentdisclosure includes a determination step and an output step. Thedetermination step is a step of, when image processing performed onimage data detects ultraviolet light, determining that a light emittingsource is a fire flame. The output step is a step of outputting adetermination result in the determination step.

A non-transitory storage medium storing a computer program according toone aspect of the present disclosure is a non-transitory storage mediumstoring a computer program configured to cause a computer system toexecute the above-described flame detection method.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures depict one or more implementation in accordance with thepresent teaching, by way of example only, not by way of limitations. Inthe figures, like reference numerals refer to the same or similarelements.

FIG. 1 is a block diagram illustrating a flame detection system and areporting system according to one embodiment of the present disclosure;

FIG. 2A is a schematic diagram illustrating an arrangement pattern ofcolor filters of a solid-state imaging device included in the reportingsystem, and FIG. 2B is a schematic diagram illustrating anotherarrangement pattern of color filters of the solid-state imaging deviceincluded in the reporting system;

FIG. 3 is a circuit diagram illustrating one of pixels of thesolid-state imaging device included in the reporting system;

FIG. 4 is a sectional view schematically illustrating the solid-stateimaging device included in the reporting system;

FIG. 5 is a timing chart of the solid-state imaging device included inthe reporting system;

FIG. 6 is a flowchart of a first operation example of the flamedetection system;

FIG. 7 is a view illustrating the first operation example of the flamedetection system;

FIG. 8 is a flowchart illustrating a second operation example of theflame detection system;

FIG. 9 is a view illustrating the second operation example of the flamedetection system;

FIG. 10 is a flowchart of a third operation example of the flamedetection system;

FIG. 11 is a view illustrating the third operation of the flamedetection system;

FIG. 12 is a flowchart of a fourth operation example of the flamedetection system;

FIG. 13 is a view illustrating the fourth operation example of the flamedetection system; and

FIG. 14 is a block diagram illustrating a flame detection system and areporting system according to a variation of the one embodiment of thepresent disclosure.

DESCRIPTION OF EMBODIMENTS

(1) Schema

A schema of a flame detection system 1 and a reporting system 10 of thepresent embodiment will be described below with reference to FIG. 1.

The flame detection system 1 according to the present embodiment is asystem applied to, for example, a hydrogen station, a hydrogen powergenerating facility, or the like and configured to detect a fire flamegenerated by hydrogen leakage. Moreover, the reporting system 10according to the present embodiment is a system configured to report anabnormality (hydrogen leakage) when a fire flame is detected by theflame detection system 1.

As illustrated in FIG. 1, the flame detection system 1 according to thepresent embodiment includes a determiner 11 and an outputter 12. Thedeterminer 11 determines whether or not a light emitting source is afire flame as a sensing target based on a result from image processingperformed on image data D0. In other words, when the image processingperformed on the image data D0 detects ultraviolet light (light having afirst wavelength), the determiner 11 determines that the light emittingsource is the fire flame. In the present embodiment, the fire flame asthe sensing target is a hydrogen flame. As used herein, the “hydrogenflame” is a fire flame generated by burning hydrogen, and at this time,only ultraviolet light is generated. The outputter 12 outputs adetermination result by the determiner 11.

As illustrated in FIG. 1, the reporting system 10 according to thepresent embodiment includes the flame detection system 1, a solid-stateimaging device 2, and a reporting unit 3. The solid-state imaging device2 is sensitive to ultraviolet light (ultraviolet radiation) and outputsthe image data D0 to the flame detection system 1. The reporting unit 3reports an abnormality in accordance with an output result of theoutputter 12 of the flame detection system 1. Specifically, whenreceiving from the outputter 12 a result representing that the hydrogenflame is detected, the reporting unit 3 reports the occurrence of theabnormality (hydrogen leakage).

According to the flame detection system 1 of the present embodiment,whether or not the light emitting source is the fire flame (hydrogenflame) is determined based on the presence or absence of the ultravioletlight in the image data D0, which enables the detection accuracy of thefire flame to be improved as compared to a case where the determinationis made based on, for example, the movement of the fire flame. Moreover,the reporting system 10 according to the present embodiment enables theoccurrence of the abnormality (hydrogen leakage) to be reported when theflame detection system 1 detects the fire flame.

(2) Details

Details of the flame detection system 1 and the reporting system 10 ofthe present embodiment will be described below with reference to FIGS. 1to 4.

As illustrated in FIG. 1, the reporting system 10 according to thepresent embodiment includes the flame detection system 1, thesolid-state imaging device 2, and the reporting unit 3. The reportingsystem 10 may further include a lens for focusing light on thesolid-state imaging device 2, a filter for controlling the wavelengthrange of light to be incident on the solid-state imaging device 2, andthe like. However, the lens has to be a lens configured to focus notonly visible light but also ultraviolet light.

(2.1) Flame Detection System

As illustrated in FIG. 1, the flame detection system 1 includes thedeterminer 11, the outputter 12, and a storage section 13. Thedeterminer 11 includes a signal processor 111.

The determiner 11 includes a microcomputer including a processor andmemory. That is, the determiner 11 is realized by a computer systemincluding a processor and memory. The processor executes an appropriateprogram, and thereby, the computer system functions as the determiner11. The program may be stored in the memory in advance, provided via atelecommunications network such as the Internet, or provided by anon-transitory storage medium such as a memory card storing the program.

The signal processor 111 performs prescribed signal processing (imageprocessing) on the image data D0 from the solid-state imaging device 2.For example, as illustrated in FIG. 2A, when the solid-state imagingdevice 2 include only blue color filters, the signal processor 111creates first image data D1 and second image data D2. The first imagedata D1 is an image created based on pixels (pixels denoted by “W” inFIG. 2A) 20 by which ultraviolet light, blue light, green light, and redlight are receivable. The second image data D2 is an image created basedon pixels (pixels denoted by “B” in FIG. 2A) 20 provided with the colorfilters. The pixels 20 by which the ultraviolet light, blue light, greenlight, and red light are receivable are hereinafter also referred to as“first pixels 20”. In the first image data D1, the pixels 20 providedwith the color filters are interpolated based on the first pixels 20located therearound. In the second image data D2, the first pixels 20are interpolated based on the pixels 20 located therearound and providedwith the color filters.

Alternatively, for example, when the solid-state imaging device 2includes blue, red, and green color filters as illustrated in FIG. 2B,the signal processor 111 creates first image data D1, second image dataD2, third image data D3, and fourth image data D4. The first image dataD1 is an image created based on pixels (pixels denoted by “W” in FIG.2B) 20 by which ultraviolet light, blue light, green light, and redlight are receivable. The second image data D2 is an image created basedon pixels (pixels denoted by “B” in FIG. 2B) 20 provided with the bluecolor filters. The third image data D3 is an image created based onpixels (pixels denoted by “R” in FIG. 2B) 20 provided with the red colorfilters. The fourth image data D4 is an image created based on pixels(pixels denoted by “G” in FIG. 2B) 20 provided with green color filters.

The determiner 11 performs a determination process based on the firstimage data D1 and the second image data D2 (or, first image data D1 tofourth image data D4) stored in the storage section 13. The determiner11 distinguishes between the hydrogen flame and a light emitting sourceother than the hydrogen flame by the determination process. As usedherein, the “light emitting source other than the hydrogen flame”includes spark discharge (e.g., lightning flash), corona discharge, afire flame of a substance containing carbon (hereinafter also referredto as a “carbon flame”), and the like. Moreover, as used herein, the“fire flame of a substance containing carbon” refers to a fire flamegenerated by burning a substance containing carbon, and at this time,ultraviolet light and visible light are generated. The determiner 11distinguishes between the hydrogen flame and the carbon flame based onthe first image data D1 and at least one of the pieces of second tofourth image data D2 to D4 which corresponds to the wavelength of thecarbon flame. When a light emitting source is detected in all of thefirst image data D1 and the at least one of the pieces of second tofourth image data D2 to D4 which corresponds to the wavelength of thecarbon flame, the determiner 11 determines that the light emittingsource is the carbon flame, and when the light emitting source isdetected only in the first image data D1, the determiner 11 determinesthat the light emitting source is the hydrogen flame.

Moreover, in the case of spark discharge and corona discharge(hereinafter also referred to as “discharge”), not only ultravioletlight but also blue light is generated. The determiner 11 distinguishesthe hydrogen flame and the discharge based on, for example, the firstimage data D1 and the second image data D2. When a light emitting sourceis detected in both the first image data D1 and the second image dataD2, the determiner 11 determines that the light emitting source is thedischarge, and when the light emitting source is detected only in thefirst image data D1, the determiner 11 determines that the lightemitting source is the hydrogen flame. That is, when the imageprocessing performed on the image data D0 detects light within awavelength range different from the wavelength range of the ultravioletlight, the determiner 11 determines that the light emitting source isnot the hydrogen flame (fire flame). In particular, when the hydrogenflame is distinguished from the discharge, the wavelength rangedifferent from the wavelength range of the ultraviolet light is thewavelength range of blue light. The wavelength range of the blue lightis, for example, 380 nm to 400 nm.

The outputter 12 outputs the determination result by the determiner 11to the reporting unit 3. In other words, when the determiner 11determines that the hydrogen flame as the sensing target is detected,the outputter 12 outputs, to the reporting unit 3, a result representingthat the hydrogen flame is detected. In the present embodiment, theoutputter 12 outputs, to the reporting unit 3, a report instructionsignal S1 for causing the reporting unit 3 to report that the hydrogenflame as the sensing target is detected.

The storage section 13 is constituted by, for example, readable/writablememory such as flash memory. The storage section 13 stores the firstimage data D1 and the second image data D2 (or, the first image data D1to the fourth image data D4) created by the signal processor 111 basedon the image data D0 sent from the solid-state imaging device 2.

(2.2) Solid-State Imaging Device

As illustrated in FIGS. 2A and 2B, the solid-state imaging device 2according to the present embodiment includes the plurality of (in theexample shown in the figure, 16) pixels 20 arranged in an m×n array (inthe example shown in the figures, m=4 and n=4). In other words, theplurality of pixels 20 (the first pixels and second pixels) are arrangedin a two-dimensional grid pattern. In FIG. 2A, the pixels 20 denoted by“W” are white, that is, the first pixels by which ultraviolet light,blue light, green light, and red light are receivable, and the pixels 20denoted by “B” are pixels (the second pixels) provided with the colorfilters through which only blue light is allowed to pass. In FIG. 2B,the pixels 20 denoted by “R” are pixels provided with the color filtersthrough which only red light is allowed to pass, and the pixels 20denoted by “G” are pixels provided with the color filters through whichonly green light is allowed to pass. In FIGS. 2A and 2B, the firstpixels 20 and the pixels 20 provided with the color filters arealternately arranged.

In the flame detection system 1 according to the present embodiment, atleast one of the plurality of pixels 20 is preferably the pixel 20provided with the color filter in order to distinguish between thehydrogen flame and the light emitting source other than the hydrogenflame. In particular, when the hydrogen flame is distinguished from thedischarge, at least one of the plurality of pixels 20 is preferably thepixel 20 provided with the blue color filter.

As illustrated in FIGS. 3 and 4, each of the plurality of pixels 20includes a first electrode 24, a photoelectric converter 25, a secondelectrode 26, an electric charge accumulator 28, a first transistor 291,a second transistor 292, and a third transistor 293. Moreover, each ofthe plurality of pixels 20 further includes a semiconductor substrate21, a pixel circuit 22, and a wiring layer 23. In the example shown inFIG. 4, three pixel circuits 22 are mounted on the semiconductorsubstrate 21.

The first electrode (lower electrode) 24 is made of, for example, amaterial such as aluminum (Al), copper (Cu), titanium nitride (TiN), orthe like suitable for semiconductor fabrication processes. The firstelectrode 24 is electrically connected via the wiring layer 23 to theelectric charge accumulator 28 provided in the pixel circuit 22.

The photoelectric converter 25 is, for example, an organic filmsensitive to ultraviolet light. The organic film is sensitive to notonly the ultraviolet light but also visible light. The photoelectricconverter 25 is located on the first electrode 24. The photoelectricconverter 25 converts light into an electric signal. Materials for thephotoelectric converter 25 are not limited to the organic film but maybe, for example, materials such as silicon, aluminum gallium nitride(AlGaN), and diamond which are sensitive to ultraviolet light.

The second electrode (upper electrode) 26 is, for example, a transparentelectrode made of indium tin oxide (ITO), zinc oxide (ZnO), or the like.The second electrode 26 is located on the photoelectric converter 25.

The protection film 27 is made of, for example, silicon nitride, siliconoxynitride, or the like.

The electric charge accumulator 28 is provided in the pixel circuit 22.The electric charge accumulator 28 accumulates electric chargesgenerated by the photoelectric converter 25. The electric chargeaccumulator 28 is, for example, P-N junction capacitance.

The first transistor (source follower transistor) 291 outputs a sourcevoltage as a signal when the electric charges accumulated in theelectric charge accumulator 28 are applied to the gate of the firsttransistor. The second transistor (reset transistor) 292 erases (resets)the electric charges accumulated in the electric charge accumulator 28from the electric charge accumulator 28. The third transistor (selectiontransistor) 293 selects any pixel 20 from the plurality of pixels 20.

Next, operation of the solid-state imaging device 2 will be brieflydescribed. Light passing through the protection film 27 and the secondelectrode 26 are converted through photoelectric conversion performed bythe photoelectric converter 25 into an electric charge (electricsignal). The electric charge obtained by the conversion performed by thephotoelectric converter 25 is accumulated in the electric chargeaccumulator 28. The electric charge accumulated in the electric chargeaccumulator 28 is applied to the gate of the first transistor 291, andthe source voltage of the first transistor 291 is output as a signal.Moreover, the electric charge accumulated in the electric chargeaccumulator 28 is erased by the second transistor 292 from the electriccharge accumulator 28.

In a circuit configuration of a general solid-state imaging device, anelectric charge is lost from the electric charge accumulator when datais read out during accumulation of the electric charge. However, in acircuit configuration of the solid-state imaging device 2 according tothe present embodiment, data is readable without losing an electriccharge accumulated in the electric charge accumulator 28. That is, thecircuit configuration of the solid-state imaging device 2 according tothe present embodiment enables non-destructive readout in which data (asignal) is read without destroying the electric charge accumulated inthe electric charge accumulator 28.

As illustrated in FIG. 5, in the solid-state imaging device 2 accordingto the present embodiment, the first transistor 291 causes the electriccharge accumulator 28 to output a signal electric charge three timesbefore the second transistor 292 resets (erases) the electric charge inthe electric charge accumulator 28 (i.e., during one electric chargeaccumulation time period). According to this method, while accumulationof electric charges in the electric charge accumulator 28 continues,data is readable during the accumulation. Therefore, this methodprovides the advantage that even when the signal electric charge is verysmall, the signal becomes easily recognizable by accumulating the signalelectric charge for a long period of time. Moreover, the advantage thatdata read out during the accumulation enables early determination.

(2.3) Reporting Unit

The reporting unit 3 is configured to report an abnormality inaccordance with the output result of the outputter 12 of the flamedetection system 1. Specifically, when the determiner 11 determines thatthe hydrogen flame as the sensing target is detected, the reporting unit3 reports the occurrence of an abnormality (hydrogen leakage). Thereporting unit 3 includes a monitor (display device) installed in, forexample, a hydrogen station. The reporting unit 3 causes the monitor todisplay a message saying, for example, “an abnormality occurred” basedon the report instruction signal S1 from the outputter 12. In this case,the reporting unit 3 may be configured to not only display the messageon the monitor but also report the occurrence of the abnormality by asound (voice, buzzer, or the like). Moreover, in this case, for example,the reporting unit 3 may be configured to notify a management company ofthe hydrogen station of the occurrence of the abnormality.

(3) Operation

Operation of the flame detection system 1 of the present embodiment willbe described below.

(3.1) First Operation Example

A first operation example of the flame detection system 1 according tothe present embodiment will be described with reference to FIGS. 6 and7. In the first operation example, a case where a hydrogen flame isdistinguished from discharge will be described. In this case, thesolid-state imaging device 2 includes blue color filters as illustratedin FIG. 2A.

In FIG. 7, “pattern 1” shows a case where neither the hydrogen flame northe discharge is detected. In FIG. 7, “pattern 2” shows a case where thehydrogen flame is detected. In FIG. 7, “pattern 3” shows a case wherethe discharge is detected. In FIG. 7, “pattern 4” shows a case whereboth the hydrogen flame and the discharge are detected. Note that shapesof the hydrogen flame and the discharge in FIG. 7 schematicallyrepresent the hydrogen flame and the discharge and are different fromactual shapes.

The determiner 11 reads first image data D1 from the storage section 13.The signal processor 111 extracts a first area R1 based on the firstimage data D1 (step ST101). At this time, the signal processor 111compares the luminance value of each pixel 20 in the first image data D1with a threshold prescribed and extracts, as the first area R1, an areain which the luminance value is larger than or equal to the threshold(step ST102). If the first area R1 is not extracted (step ST102; No),the determiner 11 determines that neither the hydrogen flame nor thedischarge exists, and the determiner 11 repeats steps ST101 and ST102.That is, this case corresponds to “pattern 1” in FIG. 7.

If the first area R1 is extracted (step ST102; Yes), the determiner 11reads second image data D2 from the storage section 13. The signalprocessor 111 extracts a second area R2 based on the second image dataD2 (step ST103). As used herein, the “second area R2” is an area whichis in the second image data D2, which is the same as the first area R1,and in which the luminance value of each pixel 20 is larger than orequal to the threshold. That is, the signal processor 111 performs acomparison between the threshold and each luminance value in the areawhich is in the second image data D2 and which is the same as the firstarea R1, and the signal processor 111 extracts, as the second area R2,the area in which each luminance value is larger than or equal to thethreshold (step ST104).

If the second area R2 is extracted (step ST104; Yes), the determiner 11determines that a light emitting source is the discharge, and theoperation returns to step ST101. This case corresponds to “pattern 3” inFIG. 7. That is, when the light emitting source is the discharge, bluelight is included, and since this blue light passes through the bluecolor filters, the blue light is extracted as the second area R2 in thesecond image data D2.

If the second area R2 is not extracted (step ST104; No), the determiner11 determines that the light emitting source is the hydrogen flame (stepST105). This case corresponds to “pattern 2” and “pattern 4” in FIG. 7.That is, when the light emitting source is the hydrogen flame, onlyultraviolet light exists, but this ultraviolet light is absorbed by theblue color filters and is thus not extracted as the second area R2 inthe second image data D2.

When the determiner 11 determines that the light emitting source is thehydrogen flame, the determiner 11 causes the outputter 12 to output thereport instruction signal S1. Then, the reporting unit 3 of thereporting system 10 receives the report instruction signal S1 from theoutputter 12 and reports the occurrence of an abnormality (hydrogenleakage). In this case, the monitor of the reporting unit 3 may becaused to display the first image data D1 and the second image data D2.

This method enables the hydrogen flame to be distinguished from thedischarge and thus reduces troubles, for example, stopping of a facilitysuch as the hydrogen station due to erroneous detection.

(3.2) Second Operation Example

A second operation example of the flame detection system 1 according tothe present embodiment will be described with reference to FIGS. 8 and9. In the second operation example, a case where a hydrogen flame,discharge, and a carbon flame (e.g., a fire flame which emits red light)are distinguished from one another will be described. In this case, thesolid-state imaging device 2 includes blue, red, and green color filtersas illustrated in FIG. 2B.

In FIG. 9, “pattern 1” shows a case where none of the hydrogen flame,the discharge, and the carbon flame is detected. In FIG. 9, “pattern 2”shows a case where the hydrogen flame is detected. In FIG. 9, “pattern3” shows a case where the discharge is detected. In FIG. 9, “pattern 4”shows a case where the carbon flame is detected. In FIG. 9, “pattern 5”shows a case where all of the hydrogen flame, the discharge, and thecarbon flame are detected. Note that shapes of the hydrogen flame, thedischarge, and the carbon flame in FIG. 9 schematically represent thehydrogen flame, the discharge, and the carbon flame and are differentfrom actual shapes.

The determiner 11 reads first image data D1 from the storage section 13.The signal processor 111 extracts a first area R1 based on the firstimage data D1 (step ST201). At this time, the signal processor 111compares the luminance value of each pixel 20 in the first image data D1with a threshold prescribed and extracts, as the first area R1, an areain which the luminance value is larger than or equal to the threshold(step ST202). If the first area R1 is not extracted (step ST202; No),the determiner 11 determines that none of the hydrogen flame, thedischarge, and the carbon flame exists, and the determiner 11 repeatssteps ST201 and ST202. This case corresponds to “pattern 1” in FIG. 9.

If the first area R1 is extracted (step ST202; Yes), the determiner 11reads second image data D2 from the storage section 13. The signalprocessor 111 extracts a second area R2 based on the second image dataD2 (step ST203). The signal processor 111 performs a comparison betweenthe threshold and each luminance value in an area which is in the secondimage data D2 and which is the same as the first area R1, and the signalprocessor 111 extracts, as the second area R2, the area in which eachluminance value is larger than or equal to the threshold (step ST204).

If the second area R2 is extracted (step ST204; Yes), the determiner 11determines that a light emitting source is the discharge, and theoperation returns to step ST201. This case corresponds to “pattern 3” inFIG. 9. That is, when the light emitting source is the discharge, bluelight is included, and since this blue light passes through the bluecolor filters, the blue light is extracted as the second area R2 in thesecond image data D2.

If the second area R2 is not extracted (step ST204; No), the determiner11 reads third image data D3 from the storage section 13. The signalprocessor 111 extracts a third area R3 based on the third image data D3(step ST205). The signal processor 111 performs a comparison between thethreshold and each luminance value in an area which is in the thirdimage data D3 and which is the same as the first area R1, and the signalprocessor 111 extracts, as the third area R3, an area in which eachluminance value is larger than or equal to the threshold (step ST206).

If the third area R3 is extracted (step ST206; Yes), the determiner 11determines that the light emitting source is the carbon flame, and theoperation returns to step ST208. This case corresponds to “pattern 4” inFIG. 9. That is, when the light emitting source is the carbon flame, redlight is included, and since this red light passes through the red colorfilters, the red light is extracted as the third area R3 in the thirdimage data D3.

If the third area R3 is not extracted (step ST206; No), the determiner11 determines that the light emitting source is the hydrogen flame (stepST207). This case corresponds to “pattern 2” and “pattern 5” in FIG. 9.That is, when the light emitting source is the hydrogen flame, onlyultraviolet light exists, but this ultraviolet light is absorbed by thered color filters and is thus not extracted as the third area R3 in thethird image data D3.

When the determiner 11 determines that the light emitting source is thehydrogen flame, the determiner 11 causes the outputter 12 to output thereport instruction signal S1. Then, the reporting unit 3 of thereporting system 10 receives the report instruction signal S1 from theoutputter 12 and reports the occurrence of an abnormality (hydrogenleakage). In this case, the monitor of the reporting unit 3 may becaused to display the first image data D1, the second image data D2, andthe third image data D3.

This method enables the hydrogen flame, the discharge, and the carbonflame to be distinguished among one another and thus reduces troubles,for example, stopping of a facility such as the hydrogen station due toerroneous detection.

Note that as illustrated in the second operation example, a generalflame (“flame of a substance containing carbon”) emits red light, andthe red light passes through the red color filters. Thus, when thespectrum of an object causing erroneous detection is known in advance,the characteristic of the filter mounted on each pixel is changed inaccordance with the spectrum, which provides the advantage that theshape of the area is more easily recognized.

(3.3) Third Operation Example

A third operation example of the flame detection system 1 according tothe present embodiment will be described with reference to FIGS. 10 and11. In the third operation example, a case where a hydrogen flame isdistinguished from discharge will be described. In this case, thesolid-state imaging device 2 includes blue color filters as illustratedin FIG. 2A.

In FIG. 11, “pattern 1” shows a case where neither the hydrogen flamenor the discharge is detected. In FIG. 11, “pattern 2” shows a casewhere the hydrogen flame is detected. In FIG. 11, “pattern 3” shows acase where the discharge is detected. In FIG. 11, “pattern 4” shows acase where both the hydrogen flame and the discharge are detected. Notethat shapes of the hydrogen flame and the discharge in FIG. 11schematically represent the hydrogen flame and the discharge and aredifferent from actual shapes.

The determiner 11 reads first image data D1 from the storage section 13.The signal processor 111 extracts a first area R1 based on the firstimage data D1 (step ST301). At this time, the signal processor 111compares the luminance value of each pixel 20 in the first image data D1with a threshold prescribed and extracts, as the first area R1, an areain which the luminance value is larger than or equal to the threshold(step ST302). If the first area R1 is not extracted (step ST302; No),the determiner 11 determines that neither the hydrogen flame nor thedischarge exists, and the determiner 11 repeats steps ST301 and ST302.This case corresponds to “pattern 1” in FIG. 11.

If the first area R1 is extracted (step ST302; Yes), the determiner 11extracts the first area R1 in each of a plurality of (in the exampleshown in the figure, three) pieces of first image data D1 which aresuccessive in time sequence (step ST303). In other words, the determiner11 determines whether or not a light emitting source is the fire flamebased on a plurality of pieces of image data D0 obtained in timesequence. Since light is emitted non-continuously in the case of thelight emitting source being the discharge, the determiner 11 determinesthat the light emitting source is the discharge when the first area R1is not successively detected in time sequence (step ST304; No), and theoperation returns to step ST301. This case corresponds to “pattern 3” inFIG. 11.

Since light is emitted continuously in the case of the light emittingsource being the hydrogen flame, the determiner 11 determines that thelight emitting source is the hydrogen flame (step ST305) when the firstarea R1 is successively detected in time series (step ST304; Yes). Inother words, when the image processing performed on the plurality ofpieces of image data D0 successively detects ultraviolet light, thedeterminer 11 determines that the light emitting source is the fireflame. This case corresponds to “pattern 2” and “pattern 4” in FIG. 11.

When the determiner 11 determines that the light emitting source is thehydrogen flame, the determiner 11 causes the outputter 12 to output thereport instruction signal S1. Then, the reporting unit 3 of thereporting system 10 receives the report instruction signal S1 from theoutputter 12 and reports the occurrence of an abnormality (hydrogenleakage). In this case, the monitor of the reporting unit 3 may becaused to display the first image data D1, the second image data D2, andthe third image data D3.

This method enables the hydrogen flame to be distinguished from thedischarge and thus reduces troubles, for example, stopping of a facilitysuch as the hydrogen station due to erroneous detection.

(3.4) Fourth Operation Example

A fourth operation example of the flame detection system 1 according tothe present embodiment will be described with reference to FIGS. 12 and13. In the fourth operation example, a case where a hydrogen flame isdistinguished from discharge will be described. In this case, thesolid-state imaging device 2 includes blue color filters as illustratedin FIG. 2A.

In FIG. 13, “pattern 1” shows a case where neither the hydrogen flamenor the discharge is detected. In FIG. 13, “pattern 2” shows a casewhere the hydrogen flame is detected. In FIG. 13, “pattern 3” shows acase where the discharge is detected. In FIG. 13, “pattern 4” shows acase where both the hydrogen flame and the discharge are detected.

The determiner 11 reads first image data D1 from the storage section 13.The signal processor 111 extracts a first area R1 based on the firstimage data D1 (step ST401). At this time, the signal processor 111compares the luminance value of each pixel 20 in the first image data D1with a threshold prescribed and extracts, as the first area R1, an areain which the luminance value is larger than or equal to the threshold(step ST402). If the first area R1 is not extracted (step ST402; No),the determiner 11 determines that neither the hydrogen flame nor thedischarge exists, and the determiner 11 repeats steps ST401 and ST402.This case corresponds to “pattern 1” in FIG. 13.

If the first area R1 is extracted (step ST402; Yes), the determiner 11causes the signal processor 111 to recognize the shape of the first areaR1 (step ST403). Here, in the case of the light emitting source beingthe hydrogen flame, hydrogen ignites due to frictional heating causedwhen a hydrogen gas is ejected from a leak spot formed in ahigh-pressure tubing, which results in a rectangular (trapezoidal) fireflame shape having two sides which face each other and which differ fromeach other by 10% or more in length (hereinafter referred to as a “firstshape M1”). In contrast, when the light emitting source is thedischarge, this results in a linear fire flame shape or a rectangularfire flame shape having two sides which face each other and which differfrom each other by less than 10% in length (hereinafter referred to as a“second shape M2”).

If the shape of the first area R1 is the second shape M2 (step ST404;Yes), the determiner 11 determines that the light emitting source is thedischarge, and the operation returns to step ST401. This casecorresponds to “pattern 3” in FIG. 11.

If the shape of the first area R1 is the first shape M1 (step ST404;No), the determiner 11 determines that the light emitting source is thehydrogen flame (step ST405). This case corresponds to “pattern 2” and“pattern 4” in FIG. 11. In other words, the determiner 11 determineswhether or not the light emitting source is the fire flame based on theshape of an ultraviolet light area detected by the image processing.

When the determiner 11 determines that the light emitting source is thehydrogen flame, the determiner 11 causes the outputter 12 to output thereport instruction signal S1 Then, the reporting unit 3 of the reportingsystem 10 receives the report instruction signal S1 from the outputter12 and reports the occurrence of an abnormality (hydrogen leakage). Inthis case, the monitor of the reporting unit 3 may be caused to displaythe first image data D1 and the second image data D2.

This method enables the hydrogen flame to be distinguished from thedischarge and thus reduces troubles, for example, stopping of a facilitysuch as the hydrogen station due to erroneous detection.

(4) Variation

The above-described embodiment is a mere example of various embodimentsof the present disclosure. Various modifications may be made to theabove-described embodiment depending on design and the like as long asthe object of the present disclosure can be achieved. Moreover,functions similar to those of the flame detection system 1 may berealized by a flame detection method, a computer program, anon-transitory storage medium storing a computer program, or the like.

A flame detection method according to one aspect includes adetermination step and an output step. The determination step is a stepof, when image processing performed on image data D0 detects ultravioletlight, determining that a light emitting source is a fire flame. Theoutput step is a step of outputting a determination result in thedetermination step.

A program according to one aspect is a program configured to cause acomputer system to execute the above-described flame detection method.The program may be stored in a non-transitory storage medium.

Variations of the above-described embodiment will be described below.Note that any of the variations to be described below may be combined asappropriate.

The flame detection system 1 or a subject that executes the flamedetection method of the present disclosure includes a computer system.The computer system includes, as hardware, a processor and memory. Thefunctions of the flame detection system 1 or the subject that executesthe flame detection method of the present disclosure may be performed bymaking the processor execute a program stored in the memory of thecomputer system. The program may be stored in the memory of the computersystem in advance or may be provided over telecommunications network.Alternatively, the program may also be distributed after having beenrecorded in some non-transitory storage medium such as a memory card, anoptical disc, or a hard disk drive, any of which is readable for thecomputer system. The processor of the computer system includes one ormore electronic circuits including a semiconductor integrated circuit(IC) or a large-scale integrated circuit (LSI). The plurality ofelectronic circuits may be collected on one chip or may be distributedon a plurality of chips. The plurality of chips may be integratedtogether in a single device or distributed in multiple devices withoutlimitation.

The function of the determiner 11 (including the signal processor 111)of the flame detection system 1 may be provided in a single device ormay be distributed in multiple devices. Still alternatively, at leastsome functions of the determiner 11 may be implemented as a cloudcomputing system as well.

In the above-described embodiment, an example in which a fire flame isthe hydrogen flame is shown, but the fire flame is not limited to thehydrogen flame but may be another fire flame as long as it is a fireflame emitting light. For example, in the case of a general flame, anemission spectrum differs between burning in the presence of sufficientoxygen (complete burning) and burning in the presence of insufficientoxygen (unburning) (the emission spectrum is blue during the completeburning and red during the unburning). As described above, adapting thecharacteristic of the filter in each case to the emission spectrum ofthe complete burning or the unburning enables the hydrogen flame, thedischarge, and the carbon flame to be distinguished from one another butalso burning states of a carbon flame (general fire flame) to bedistinguished from each other.

The above-described embodiment uses the color filters through each ofwhich only specified light is allowed to pass, but, for example, animage data in a state where no light is emitted from a light emittingsource may be defined as a reference data, and a filter function may berealized based on a difference from the reference data. In this case, afilter (UV filter, RGB filter, or the like) for identifying the lightemitting source may be omitted.

For example, when the hydrogen flame is distinguished from thedischarge, light within a wave length range longer than the wave lengthrange of blue light included in the discharge is not necessary, andtherefore, the solid-state imaging device 2 may be provided with afilter configured to block the light within the wavelength range longerthan the wave length of the blue light.

In the above-described embodiment, an example has been described inwhich the solid-state imaging device 2 includes the pixels 20 providedwith the color filters and pixels 20 by which ultraviolet light, bluelight, green light, and red light are receivable. In contrast, thesolid-state imaging device 2 may include, for example, the pixels 20provided with the color filters and pixels on which UV filterstransmissive to only ultraviolet light are mounted.

In the above-described embodiment, the solid-state imaging device 2 isincluded in the reporting system 10, but the solid-state imaging device2 may be included in the flame detection system 1 as illustrated in FIG.14. In other words, the flame detection system 1 may include thesolid-state imaging device 2, the determiner 11, and the outputter 12.

SUMMARY

As described above, a flame detection system (1) of the first aspectincludes a determiner (11) and an outputter (12). The determiner (11) isconfigured to, when image processing performed on image data (D0)detects ultraviolet light, determine that a light emitting source is afire flame. The outputter (12) is configured to output a determinationresult by the determiner (11).

This aspect determines whether or not the light emitting source is thefire flame based on the presence or absence of the ultraviolet light inthe image data (D0), which enables the detection accuracy of the fireflame to be improved as compared to a case where the determination ismade based on, for example, the movement of the fire flame.

In a flame detection system (1) of a second aspect referring to thefirst aspect, the determiner (11) is configured to, when the imageprocessing detects light within a wavelength range different from awavelength range of the ultraviolet light, determine that the lightemitting source is not the fire flame.

This aspect enables the fire flame and a light emitting source otherthan the fire flame to be distinguished from each other.

In a flame detection system (1) of a third aspect referring to thesecond aspect, the wavelength range of the light is a wavelength rangeof blue light.

This aspect enables the fire flame and an ultraviolet light emittingsource such as the discharge (including lightning flash) to bedistinguished from each other.

In a flame detection system (1) of a fourth aspect referring to any oneof the first to third aspects, the determiner (11) determines whether ornot the light emitting source is the fire flame based on a plurality ofpieces of image data (D0) obtained in time sequence.

This aspect further improves the detection accuracy of a fire flame ascompared to a case where determination is made based on one image data.

In a flame detection system (1) of a fifth aspect referring to thefourth aspect, the determiner (11) is configured to, when the imageprocessing performed on the plurality of pieces of image data (D0)successively detects the ultraviolet light, determine that the lightemitting source is the fire flame.

This aspect enables ultraviolet light to be consecutively detected intime sequence when a fire flame includes the ultraviolet light and thusenables the accuracy of distinguishing between the fire flame and theultraviolet light emitting source other than the fire flame to beimproved.

In a flame detection system (1) of a sixth aspect referring to any oneof the first to fifth aspects, the determiner (11) is configured todetermine whether or not the light emitting source is the fire flamebased on a shape (a first shape M1, a second shape M2) of an ultravioletlight area (a first area R1) detected by the image processing.

With this aspect, whether or not the light emitting source is the fireflame is determined based on the shape of the ultraviolet light.

A reporting system (10) according to a seventh aspect includes the flamedetection system (1) of any one of the first to sixth aspects, asolid-state imaging device (2), and a reporting unit (3). Thesolid-state imaging device (2) is sensitive to ultraviolet light and isconfigured to output the image data (D0). The reporting unit (3) isconfigured to report an abnormality in accordance with an output resultof the outputter (12).

This aspect enables the occurrence of the abnormality to be reportedwhen the flame detection system (1) detects the fire flame.

In a reporting system (10) according to an eighth aspect referring tothe seventh aspect, the solid-state imaging device (2) includes aplurality of pixels (20) arranged in an array. Each of the plurality ofpixels (20) includes a first electrode (24), a photoelectric converter(25), an electric charge accumulator (28), a second electrode (26), afirst transistor (291), a second transistor (292), and a thirdtransistor (293). The photoelectric converter (25) is located on thefirst electrode (24) and is configured to convert light into an electricsignal. The electric charge accumulator (28) is electrically connectedto the first electrode (24) and is configured to accumulate an electriccharge generated by the photoelectric converter (25). The secondelectrode (26) is located on the photoelectric converter (25). The firsttransistor (291) is configured to cause the electric charge accumulator(28) to output the electric charge accumulated in the electric chargeaccumulator (28). The second transistor (292) erases the electric chargeaccumulated in the electric charge accumulator (28) from the electriccharge accumulator (28). The third transistor (293) selects any pixel(20) from the plurality of pixels (20). The photoelectric converter (25)is an organic film.

This aspect enables the occurrence of the abnormality to be reportedwhen the flame detection system (1) detects the fire flame.

A flame detection method according to a ninth aspect includes adetermination step and an output step. The determination step is a stepof, when image processing performed on image data (D0) detectsultraviolet light, determining that a light emitting source is a fireflame. The output step is a step of outputting a determination result inthe determination step.

This aspect enables the detection accuracy of the fire flame to beimproved.

A non-transitory storage medium according to a tenth aspect is anon-transitory storage medium storing a computer program configured tocause a computer system to execute the flame detection method of theninth aspect.

This aspect enables the detection accuracy of the fire flame to beimproved.

A flame detection system (1) of an eleventh aspect includes asolid-state imaging device (2), a determiner (11), and an outputter(12). The solid-state imaging device (2) includes first pixels (20) andsecond pixels (20) arranged in a two-dimensional grid pattern and thesecond pixels (20) are provided with filters. The determiner (11) isconfigured to create first image data (D1) from first pixel informationof the first pixels (20). The determiner (11) is configured to createsecond image data (D2) from second pixel information of the secondpixels (20). The determiner (11) is configured to determine, based on aluminance value of each of the first image data (D1) and the secondimage data (D2), that an area from which light having a first wavelengthis emitted represents a fire flame. The outputter (12) is configured tooutput a determination result by the determiner (11).

With this aspect, whether or not the light emitting source is the fireflame is determined based on the luminance value of each of the firstimage data (D1) and the second image data (D2).

The configurations according to the second to sixth aspects are notconfigurations essential for the flame detection system (1) and mayaccordingly be omitted.

The configuration according to the eighth aspect is not a configurationessential for the reporting system (10) and may accordingly be omitted.

While the foregoing has described what are considered to be the bestmode and/or other examples, it is understood that various modificationsmay be made therein and that the subject matter disclosed herein may beimplemented in various forms and examples, and that they may be appliedin numerous applications, only some of which have been described herein.It is intended by the following claims to claim any and allmodifications and variations that fall within the true scope of thepresent teachings.

1. A flame detection system, comprising: a determiner configured to,when image processing performed on image data detects ultraviolet light,determine that a light emitting source is a fire flame; and an outputterconfigured to output a determination result by the determiner.
 2. Theflame detection system of claim 1, wherein the determiner is configuredto, when the image processing detects light within a wavelength rangedifferent from a wavelength range of the ultraviolet light, determinethat the light emitting source is not the fire flame.
 3. The flamedetection system of claim 2, wherein the wavelength range of the lightis a wavelength range of blue light.
 4. The flame detection systemaccording to claim 1, wherein the determiner determines whether or notthe light emitting source is the fire flame based on a plurality ofpieces of image data obtained in time sequence.
 5. The flame detectionsystem of claim 4, wherein the determiner is configured to, when theimage processing performed on the plurality of pieces of image datasuccessively detects the ultraviolet light, determine that the lightemitting source is the fire flame.
 6. The flame detection systemaccording to claim 1, wherein the determiner is configured to determinewhether or not the light emitting source is the fire flame based on ashape of an ultraviolet light area detected by the image processing. 7.A reporting system, comprising: the flame detection system according toclaim 1; a solid-state imaging device sensitive to ultraviolet light andconfigured to output the image data; and a reporting unit configured toreport an abnormality in accordance with an output result of theoutputter.
 8. The reporting system of claim 7, wherein the solid-stateimaging device includes a plurality of pixels arranged in an array, eachof the plurality of pixels includes a first electrode, a photoelectricconverter located on the first electrode and configured to convert lightinto an electric signal, an electric charge accumulator electricallyconnected to the first electrode and configured to accumulate anelectric charge generated by the photoelectric converter, a secondelectrode located on the photoelectric converter, a first transistorconfigured to cause the electric charge accumulator to output theelectric charge accumulated in the electric charge accumulator, a secondtransistor configured to erase the electric charge accumulated in theelectric charge accumulator from the electric charge accumulator, and athird transistor configured to select any pixel from the plurality ofpixels, and the photoelectric converter is an organic film.
 9. A flamedetection method comprising: a determination step of, when imageprocessing performed on image data detects ultraviolet light,determining that a flame is a fire flame; and an output step ofoutputting a determination result in the determination step.
 10. Anon-transitory storage medium storing a computer program configured tocause a computer system to execute the flame detection method of claim9.
 11. A flame detection system, comprising: a solid-state imagingdevice including first pixels and second pixels arranged in atwo-dimensional grid pattern, the second pixels being provided withfilters; a determiner configured to create first image data from firstpixel information of the first pixels, create second image data fromsecond pixel information of the second pixels, and determine, based on aluminance value of each of the first image data and the second imagedata, that an area from which light having a first wavelength is emittedrepresents a fire flame; and an outputter configured to output adetermination result by the determiner.